Wireless communication has rapidly evolved over the past decades. Even today, when high performance and high bandwidth wireless communication equipment is made available there is demand for even higher performance at a higher data rates, which may be required by more demanding applications.
Video signals may be generated by various video sources, for example, a computer, a game console, a Video Cassette Recorder (VCR), a Digital-Versatile-Disc (DVD), a Blu-ray (BR) disk player, or any other suitable video source. In many houses, for example, video signals are received through cable or satellite links at a Set-Top Box (STB) located at a fixed point.
In many cases, it may be desired to place a screen or projector at a location in a distance of at least a few meters from the video source. This trend is becoming more common as flat-screen displays, e.g., plasma or Liquid Crystal Display (LCD) televisions are hung on a wall. Connection of such a display or projector to the video source through cables is generally undesired for aesthetic reasons and/or installation convenience. Thus, wireless transmission of the video signals from the video source to the screen is preferred.
WHDI—Wireless Home Digital Interface is a standard for wireless high-definition video connectivity between a video source (e.g. cable box) and video sink (e.g. display). It provides a high-quality, uncompressed wireless link which can support delivery of equivalent video data rates of up to 3Gbit/s (including uncompressed 1080 p) in a 40 MHz channel within the 5 GHz and 720 p) can be delivered on a single 20 MHz channel in the 5 GHz unlicensed band, conforming to worldwide 5 GHz spectrum regulations. Range is beyond 100 feet (30 m), through walls, and latency is less than one millisecond.
The original WHDI design utilizes RF communication signals in the 5 GHz band thus providing a communication channel bandwidth of 20-40 MHz. Since line-of-sight (LOS) isn't required between transmitters and receivers operating in the 5 GHz band, multiple antennas are often used in a Multiple-Input-Multiple-Output (MIMO) arrangement, thereby increasing the effective bandwidth and thus improving data transmission speed, signal quality and error protection.
Future WHDI implementations may use RF signals in the 60 GHz band, providing a larger communication channel bandwidth (e.g. 2 GHz), thereby increasing data transmission rate, data protection and/or integrity of the data. Since RF signals in the 60 GHz band have a degraded Signal-to-Noise-Ratio (SNR) and/or dynamic range compared to the 5 GHz band, signals may be transmitted using focused beams and LOS between transmitters and receivers.
High quality (i.e. low noise with large dynamic range) amplifiers, digital-to-analog and analog-to-digital converters are desirable for both current and future video transmission technologies, including current and future WHDI based technologies. However, there is usually a tradeoff between low noise and dynamic range in amplifiers and converters. Thus, an additional challenge in implementing video transmission systems is the crest factor or peak-to-average ratio (PAR), i.e. the ratio of the instantaneous peak value to the root-mean-square (RMS) average value, of video data signals. Since edges and/or effects occur spontaneously in video data, a digital representation of the video data may contain many unexpected peaks resulting in a substantially high PAR. These spatially localized relatively high peeks can be detrimental or detract from the ability of amplifiers and converters to accurately sample, transmit, receive, synthesize and/or otherwise process portions of a frame of a relatively high bandwidth video signal.
There is thus a need in the field of wireless communication for improved methods, circuits, devices and systems for transmission of video data. There is yet a further need for improved methods, circuit, devices and systems of compensating for energy variations in transmission energy levels associated with different video frames and different video frame blocks associated with a video transmission. There is yet a further need for improved methods, circuits, devices and system of maintaining relatively stable (e.g. substantially constant) transmission power output for video transmitters.